This invention relates to mechanisms such as engines, compressors, pumps, or the like, of either the rotary or the reciprocating variety. More specifically, the invention relates to improved means for ensuring the presence of adequate contact stress at the interface of two housing components defining a chamber to preclude gas leakage.
In housings for pumps, engines, compressors, or the like, as, for example, in reciprocating mechanisms of the foregoing type, cylinder heads are commonly attached to the block by means of cap screws or studs with a gasket interposed between the two elements. Where the cylinder is defined by a cylinder liner, it is often formed to project from the surface of the block an amount on the order of a few thousandths of an inch. The usual interposed gasket is formed to be somewhat thicker in the vicinity of the liner, generally by embedding a wire ring within the gasket in a position to be aligned with the projecting portion of the cylinder liner. As a consequence, the gasket will load more heavily at its point of contact with the liner projection and the head, thus preventing leakage of high pressure gas during operation.
In other constructions, the gasket may be made more rigid at its point of alignment with the cylinder liner. The foregoing approaches taken by the prior art are relatively sensitive to manufacturing tolerances. Not only is precision of manufacturing of the various parts of considerable concern, but one must also consider the respective rigidities of the elements being clamped and the ability of the clamping means, normally bolts, and gasket elements to store enough energy in the form of elastic deformation so that contact stress sufficient to maintain a seal is maintained in spite of yielding or fretting of the parts over a prolonged period.
In typical rotary mechanisms, relatively low contact stresses are present between intermediate housing and end housing components and O-rings are typically employed to establish a seal. However, because the stresses are low, combustion or compressed gases may leak into the gap and cause deterioration of the O-rings, resulting in water from a cooling system seeping into the operating chamber of the mechanism. Even resort to high temperature resistant polymers, as the material for formation of the O-ring, has not cured the problem.